Materials containing non-naturally occurring levels of certain organic or inorganic components rendering the material potentially harmful to human health or the environment have been defined as hazardous by the United States Environmental Protection Agency and must be treated and/or disposed of in an appropriate manner
Incineration is a preferred method for the destruction of hazardous organic substances. However, wastes classified as hazardous often contain mixtures of several substances including hazardous inorganic components such as heavy metals. If wastes containing both an organic component and a heavy metal component are incinerated, a fraction of the metal(s) present will be vaporized and exit the incineration zone along with the flue gas, thus creating a new pollution control problem. Consequently, incineration of wastes containing both an organic component and a metal component requires either the removal of the metals prior to incineration, or removal of the metals from the flue gas prior to its discharge to the environment. Significant disadvantages are associated with either approach.
Innovative thermal processes to destroy hazardous organic wastes have been proposed. See, e.g., H. Freeman, "Innovative Thermal Hazardous Waste Treatment Processes", (Noyes Publications, Park Ridge, N.J., 1985) where such thermal processes were organized in generic categories: wet oxidation, chemical transformation, molten glass, fluidized bed incineration, pyrolysis, molten salt, advanted incinerators, electric reactors, and plasma systems. Given that there is a broad range of hazardous materials to be treated and that physically and chemically effective, economical, emission free treatment must be done under a variety of conditions (sometimes on-site), a range of methods is needed. None of these approaches in itself is sufficient for the treatment of all hazardous materials, and taken in aggregate, existing technology is not sufficient.
As an alternative to thermal processes, hazardous materials containing a mixture of organic(s) and heavy metal(s) (or other hazardous inorganic components) can be set in Portland cement. While this approach is superior to typical thermal processes with respect to the immobilization of the inorganic component, it is inferior to thermal processes with respect to the organic component. Unlike thermal processes, such immobilization methods may not result in a destruction of the organic components which in many instances may be classified as hazardous. Furthermore, the loading must be kept small in order to obtain quality product.
In a further alternative, activated carbon has been used to sorb various components. When the adsorptive capacity of a particular quantity of activated carbon has been exhausted, however, the spent activated carbon must be land-filled, incinerated or regenerated, none of which has proven to be practical and economical to date, particularly when the sorbed components are classified as hazardous.
Consequently, a need has remained for a process for the treatment of hazardous materials containing a thermochemically destructible component.